Left Atrial Strain and Cryptogenic Stroke

Inclusion Criteria: * Adult patients (age \> 18 years and \< 80 years) who had a complete transthoracic echocardiography (TTE) exam at the University of Pittsburgh Medical Center (UPMC) Presbyterian Echocardiography Lab with a referral diagnosis of suspected stroke. 2- Patients with an established diagnosis of stroke by stroke neurologists. 3- Patients in sinus rhythm documented at the time of referral. 4- Availability of adequate echocardiographic images for strain quantification. 5- Clinical follow-up data available for evaluation of study endpoints, including stroke recurrence, atrial fibrillation development, and mortality. 6- Patients from collaborating centers will be included with de-identified echocardiographic images and clinical data meeting the above criteria. Exclusion Criteria: Incomplete or technically difficult transthoracic echocardiography (TTE) studies and studies from subjects younger than 18 years of age will be excluded. Additional exclusion criteria include: 1- Pre-existing atrial fibrillation (AF): Patients with a documented history AF prior to the index echocardiography study will be excluded because it is well established that AF justifies cryptogenic stroke requiring anticoagulation. 2 -Structural heart disease: Patients with significant structural abnormalities, such as moderate or severe mitral stenosis, moderate or severe mitral regurgitation, prosthetic heart valves, devices in the left atrium, atrial septal defect or patent foramen ovale will be excluded as these conditions are known causes of stroke and abnormal left atrial function. 3- Coagulopathy: Patient having disease leading to hypercoagulable (thrombus formation) state will be excluded (presence of cancer, antiphospholipid antibodies, hematological diseases). 4- Inadequate clinical follow-up: Patients with insufficient follow-up data or missing medical records that preclude evaluation of study endpoints (e.g., stroke recurrence, AF development) will be excluded unless death is documented. 5- Poor image quality for strain analysis: Patients having echo exams with inadequate image quality that prevent reliable strain quantification will be excluded. \-